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.Dd February 11, 2013
.Dt VFS_BUSY 9
.Os
.Sh NAME
.Nm vfs_busy
.Nd "marks a mount point as busy"
.Sh SYNOPSIS
.In sys/param.h
.In sys/mount.h
.Ft int
.Fn vfs_busy "struct mount *mp" "int flags"
.Sh DESCRIPTION
The
.Fn vfs_busy
function marks a mount point as busy by incrementing
the reference count of a mount point.
It also delays unmounting by sleeping on
.Fa mp
if the
.Dv MNTK_UNMOUNT
flag is set in
.Fa mp->mnt_kern_flag
and the
.Dv MBF_NOWAIT
flag is
.Em not
set.
.Pp
Its arguments are:
.Bl -tag -width ".Fa flags"
.It Fa mp
The mount point to busy.
.It Fa flags
Flags controlling how
.Fn vfs_busy
should act.
.Bl -tag -width ".Dv MBF_MNTLSTLOCK"
.It Dv MBF_NOWAIT
do not sleep if
.Dv MNTK_UNMOUNT
is set.
.It Dv MBF_MNTLSTLOCK
drop the mountlist_mtx in the critical path.
.El
.El
.Sh RETURN VALUES
A 0 value is returned on success.
If the mount point is being
unmounted and MBF_NOWAIT flag is specified
.Er ENOENT
will be returned.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ENOENT
The mount point is being unmounted
.Dv ( MNTK_UNMOUNT
is set).
.El
.Sh SEE ALSO
.Xr vfs_unbusy 9
.Sh AUTHORS
This manual page was written by
.An Chad David Aq Mt davidc@acns.ab.ca .
